Abrasive sleeve and method of forming the same



Jan. 25, 1938. D: E. MULHOLLAND ,106,186

ABRASIVE SLEEVE AND METHOD OF FORMING THE SAME I Filed Nov. .2, 19:6 2Sheets-Sheet 1 gym- [and

Jan. 25, 1938. I MULHQLLAND 2,106,186

ABRASIVE SLEEVE AND METHOD OF FORMING THE SAME Fil ed Nov. 2, 1936 2Sheets-Sheet 2 Y K 3 .Dam'd Emu/1401 [and Patented 38.11.25, 1938 tPATENT HCE RASEVE SLEEVE AND METHOD OF FORM- ING THE-SAME tan a.Mlllhonfl,

Application November 2, 1936, Serial No. 18,845

18 Claims.

defects usually found in rolled metal sheets, particularly those whichare relatively wide, and to obtain a fundamental surface condition aswell as the desired surface finish, it has heretofore been necessary tosubject the sheets to repeated abrading operations. These operationsinclude roughing, intermediate and finishing steps. The roughing isaccomplished by repeatedly subjecting the sheets to the action of arotating wheel or roll provided with coarse abrasive grains which makerather deep scratches on the work so as to remove sufficient metal toobliterate the surface defects. finishing steps, the metal between thecoarse 25 scratches in the surface is removed until the scratchesthemselves are no longer visible.

In the past, these abrading operations have been performed either byflexible belts or by flexible wheels which are made of disks of muslinThe peripheries of these belts and wheels are coated with glue andabrasive grains which break into small segments during the abradingaction and thus gives effect to the flexible character of the wheel orbelt. The sheets are-presented to the flexible wheels or belts invarious mechanical ways, depending upon the equipment used and three orfour wheels or belts each coated with a different grain size isnecessary in the roughing, intermediate and finishing operations and thesheets must be passed back and forth in contact with each of them manytimes.

A high degree of skill is required to set up 45 these wheels or beltsand to maintain them in proper condition for efficient work. Varyingweather conditions, such as either high or low humidity, seriouslyaifect their efic'iency and shorten their work life.

50 Even though it is highly desirable to provide metal sheets with amore or less coarsely ground or toothed surface in order to promote theadhesion thereto of coatings, such aszinc, vitreous enamel, lacquer,paint, etc., the high cost of doing 55 this work by flexible wheels andbelts has pre- -In the subsequent intermediate and I or the like pressedtogether on rotatable shafts vented finishing sheets in this manner toany considerable extent.-

The present invention has for its principal object the production of anabrasive sleeve capable of imparting to metal sheets a fundamental sur-5 face-condition in a single pass.

Another object of the invention is to provide improved .means forconnecting the abrasive sleeve to a rotatable drum.

A primary feature of the invention consists in forming an abrasivesleeve by spirally winding a strip of abrasive material around a taperedmandrel to form a sleeve having a tapered outer surface and insubsequently modifying the sleeve to provide it with a cylindrical outer35 each convolution of the wire and in subsequently winding a strip ofabrasive material around the mandrel so as to cover the wire and fillthe spaces between the convolutions thereof.

Another feature of the invention consists in forming an abrasive sleeveby spirally winding 2. strip'of rubber bonded abrasive material around amandrel with the edges of each convolution of the strip in abuttingrelation and in subsequently .vulcanizing the material.

Another feature of the invention consists in providing a substantiallyrigid abrasive sleeve having a continuous outer surface and an innersurface adapted to have engagement with a driving drum.

o .A further feature of the invention consists in 5 providing anabrasive sleeve with a tapered inner surface and a cylindrical outersurface.

A still further feature of the invention consists x in providing anabrasive sleeve with a continuous outer surface consisting of abrasivegrains bonded 40 in rubber and with an inner surface including acircumferentially extending metallic reinforcement.

Another feature of the invention consists in providing an abrasivesleeve with a tapered inner surface for encircling a rotatable drumhaving a tapered periphery and in associating therewith means formaintaining the inner surface of the sleeve in frictional engagementwith the periphery of the drum.

Other features of the invention, residing in advantageous forms,combinations and relations of parts, will hereinafter appear and bepointed ;out in the claims.

In the drawings,

. process of being formed.

' interlocks with the wire after being compressed Figure 1 illustratesthe abrasive sleeve in the Figure Z is an enlarged detail sectional viewtaken on line 2-2 of Figure 1.

Figure 3 is a view similar to Figure 2, illustrating the manner in whichthe abrasive material and. vulcanized.

Figure 4 is a side elevational view of the completed sleeve on theforming mandrel, the dotted lines indicating the outline of the sleeveprior to being trimmed.

Figure 5 is a transverse sectional view of the strip of rubber bondedabrasive material.

Figure 6 is a transverse sectional view of the wire reinforcement.

Figure 7 is a longitudinal sectional view of the completed abrasivesleeve. 1

Figure'8 is a side elevational view of the polishing and work supportingrolls of a polishing machine illustrating the manner of mounting theabrasive sleeve on the polishing roll.

Referring more particularly to the drawings, in indicates thecomparatively rigid abrasive sleeve which is formed by first helicallywinding a wire ll about a mandrel I2 sothat the convolutions thereof arespaced from each other and then helically winding a strip of rubberbonded. abrasive material about the mandrel with its convolutions inabutting engagement. The wire i i is preferably of generally rectangularshape in cross section having its outer corners rounded and providedwith longitudinally extending slots. or recesses H in its side faces.Before being wound around the mandrel which, for a purpose as willhereinafter appear, has a tapered periphery,the wire is securelyfastened as indicated at P5 to the mandrel adjacent one end thereof. Itis then spirally wound about the mandrel in such manner that theconvolutions thereof will be spaced apart a distance equal to the widthof the abrasive strip minus the width of the wire and secured to themandrel adjacent its opposite end, as indicated at l6.

The rubber bonded abrasive material is preferably made by compoundingpure gum stock with sulphur and the usual commercial accelerators andmixing the compound with abrasive grains of a size depending upon thecharacter of finish desired on a rubber mill whose rolls turn atdifferent rates of speed. The sheeted material is folded and refolded asthe abrasive grains are added and it is repeatedly passed through therolls until the rubber bondand grains form as homogeneous a body 'aspossible. While the sheeted material is still in'a plastic conditionfrom the heat generated in mixing, it is cut into narrow strips and fedinto the hopper of a machine commonly known in the rubber industry as atube mill. Such machines are used for forming rubber stock into tubesand solid shapes before vulcanizing and they are provided with acylinder having a die at one end behind which a screw operates for Afterthe abrasive strip has been wound around v the mandrel and its endssecured in any suitable manner, the sleeve thus formed, while still onthe mandrel, is wrapped tightly with wet fabric and it is thenvulcanized. Not only do the convolutions of.,,the abrasive strip uniteto form a unitary sleeve during vulcanization, but the fabric wrappingcontracts and subjects the rubber" of the mandrel and its outer surfacewill be of cylindrical form. Thus it will be perceived that an abrasivesleeve is produced having a cylindrical outer surface and a taperedinner surface,'the latter being formed in part by a helical wire whichis keyed and bonded to the abrasive material.

By providing the sleeve with a tapered inner surface, a drivingconnection between the sleeve and the rotating drum 1 8 may be effectedby friction and the unsatisfactory clamping means heretofore employedfor securing an abrading sleeve to a rotating drum-may be entirelyeliminated, as well as keys, feathers and the like. For this purpose,the periphery of the drum I 8 is formed.

with a taper of the same order as the inside taper of the sleeve and,while anysuitable means may be employed for exerting a force on thesleeve in a direction parallel with its axis so as to maintain it infrictional engagement with the drum, it is'preferred to employ tworing-like members I! and 20 which are mounted on the smaller end'of thedrum. The ring-like member I9 is removably fastened to the drum by setscrews 2|, while the ring-like member 20 is movable axially thereof; andinterposed between the two are a plurality of coil springs 22 whichcause ring 20 to exert a pressure on the sleeve suflicient to hold theinner surface thereof in intimate contact with the outer surface of thedrum. The force exerted on the sleeve by its engagementwith the worktending to rotate it relatively to the drum is less than'that requiredto overcome the friction between the two members when they aremaintained in intimate contact by the retaining ring 20.

It will be appreciated that, since the convolutions of the wire aresupported laterally by the abrasive materialbetween them, the wireeffectively resists radial forces acting on the'sleeve induced bywedging it on the drum which might possibly be of a magnitude sufficientto rupture the abrasive material. The helical wire which is inengagement with the driving drum serves, therefore, as an effectivereinforcementior the rubber bonded abrasive material. Although thesleeve is comparatively rigid, it is probable, especially whenconsiderable time elapses between the time it is made and the time it isused, that it might get somewhat out of round. However, the constructionof the sleeve is such that itmay be easily reshaped to cause its innersurface to again v assume true conical form so as to intimately contactthe periphery of the driving drum by merely heating it in hot water tosoften the bonded abrasive material.

'- What I claim is:

l. The method of formingan abrasive sleeve consisting of spirallywinding a strip of abrasive material around a tapered mandrel to form asleeve having a tapered outer surface, and subsequently modifying thesleeveto provide it with a cylindrical outer surface.

2. The method of formingan abrasive sleeve consisting of spirallywinding a strip of abrasive material about a tapered mandrel to form asleeve having tapered inner and outer surfaces, and subsequentlytrimmingthe outer surface of the sleeve to cylindrical form.

3. The method of forming an abrasive sleeve consisting of spirallywinding 9. wire around a mandrel with spaces between each convolution ofthe wire, and subsequently winding a. strip of abrasive material aroundthe mandrel so as to cover. the wire and fill the spaces between theconvolutions' thereof.

4. The method of forming an abrasive sleeve consisting of spirallywinding a wire around a mandrel with spaces between each convolution ofthe wire, and subsequently covering the wire and filling the spacesbetween the convolutions thereof by spirally winding a strip of abrasivematerial around the mandrel with portions of the side edges of eachconvolution of the strip in abutting relation.

5. The method of forming an abrasive sleeve consisting of winding a wirehaving recessed side edges around a mandrel to form a helix with spacesbetween the convolutions thereof, subsequently covering the wire andfilling the spaces between said convolutions by spirally winding a stripof abrasive material around the mandrel, and then compressing theabrasive material to force portions thereof into the recessed side edgesof the wire.

6. The method of forming an abrasive sleeve consisting of spirallywinding a strip of rubber bonded abrasive material around a mandrel withthe edges of each convolution of the strip in abutting relation, andsubsequently vulcanizing said material.

7. The method of forming an abrasive sleeve consisting of spirallywinding a wire around a mandrel to form a helix with spaces between thethenlvulcanizing said material.

8. The method of forming an abrasive sleeve consisting of spirallywinding a wire around a mandrel to form a helix with spaces between theconvolutions thereof, subsequently covering the wire and filling thespaces between the convolutions thereof by spirally winding a strip ofrubber bonded abrasive material around the mandrel, and 'thenvulcanizing the material under pressure.

9. The method of forming an abrasive sleeve consisting of spirallywinding a wire around a mandrel to form a helix with spaces between theconvolutlons thereof, subsequently cdvering the wire by spirally windingabout the mandrel pared sleeve covering the wire and filling the spacesbetween the convolutions thereof, and I then grinding the outer surfaceof the sleeve to cylindrical form. 11. An abrasive sleeve adapted toencircle rotatable drum of a polishing machine, said sleeve having acontinuous outer surface consisting of abrasive grains bonded in rubberand having an inner surface including a circumferentially extendingmetallic reinforcement of spiral form.

12. An abrasive sleeve adapted to encircle a rotatable drum of apolishing machine, said sleeve having a continuous outerv surfaceconsisting of abrasive grains bonded in rubber and having a taperedinner surface formed in part by,

abrasive grains bonded in rubber and in part ing an inner surfaceincluding a spirally wound.

wire adapted to frictionally engage the periphery of said drum. 7

14. An abrasive sleeve adapted to encircle a rotatable drum of apolishing machine, said sleeve consisting of abrasive grains bonded inrubber and having a continuous outer surface, and a helically wound wirehaving spaced convolutions embedded-in the inner surface of the sleeve.

15. In combination in a polishing machine, a rotatable drum having astraight tapered periphery, an abrasive sleeve encircling said drumprovided with a smooth inner surface formed in part by portions of saidsleeve and in part by metal segments partially embedded in said sleeve,said surface having a taper of substantially the same order as the taperof the drum, and means for maintaining the inner surface of the sleevein frictional engagement with the periphery of the drum.

16. In combination in a polishing machine, a rotatable .drum having atapered periphery, an abrasive sleeve encircling said drum provided withan inner surface formed in part by portions of said sleeve and in partby metal segments partially embedded in said sleeve, said surface havinga taper of. substantially the same order as the taper of the drum, anda-collar encircling said drumand movable axially thereof for maintainingthe inner surface of the sleeve in frictional engagement with theperiphery of the drum.

1'7. In combination in a-polishing machine, a

rotatable drum having a tapered periphery, an

abrasive sleeve encircling said drum provided with an inner surfacehaving a tenet of substantially the same order as the taper of the drum,and spring means carried by the drum for constantly urging said sleevein a direction to maintain the inner suriace thereof in frictionalengagement with the drum.

18. An abrasive sleeve comprising abrasive grains in a bonding materialadapted to encircle and frictionally engage the rotatable drum ofapolishing machine, said sleeve having a tapered 'inner surface formedin part by portions of said sleeve and in part by metal segmentsvpartially embedded in said sleeve, said sleeve being removable fromsaid drum without destructive effort. v g

' DAVID E. MULHOILAND.

